Drilling mud

ABSTRACT

The drilling mud with a lowered coefficient of friction comprising a silicate-based mud and a lubricant selected from the group comprising glycosides, alkylpolyalkoxyalcohols, alcohol ester polymers, amine phosphates, starch and combinations thereof.

[0001] This invention relates to a drilling mud with a loweredcoefficient of friction, in particular a water-based drilling mudcontaining silicates. Such a drilling mud is referred to in thespecification and the claims as silicate-based mud.

[0002] During drilling, a drilling mud is used to help cool the drillbit and flush debris from the well bore. The drilling mud can causeadditional friction between the mud and the bore hole wall and the mudand the metal components of the drilling operation, such as the casing,drill pipe and drill bit. This additional friction slows the drillingoperation by reducing the drilling rate and the rate of penetration. Theadditional friction also reduces the variability of the drillingoperation itself, in particular the degree of well bore deviation thatmay be drilled.

[0003] A silicate-based mud has a high coefficient of friction againstrock or metal when compared to an oil-based or a synthetic-based mud,which is a drilling mud based on a synthetic hydrocarbon oil. However,the oil-based and synthetic-based mud presents certain environmentalconcerns and wells in certain locations may not be drilled using thelower friction mud. In addition, a synthetic-based mud is typically muchmore expensive than a silicate-based mud, making the mud based on asynthetic hydrocarbon oil economically less desirable. A silicate-basedmud is preferred environmentally but exhibits a high coefficient offriction between the mud and the well bore and metal components.Typically a more traditional silicate-based mud has a lubricitymeasuring in the range of 0.3 or higher. It is desirable to lower thecoefficients of friction in order to increase drilling rates and therate of penetration. An additional advantage to a mud having a lowercoefficient of friction is that it can be used in drilling a deviatedwell bore.

[0004] It is an object of the present invention to provide a silicate orwater-based mud with a coefficient of friction at least comparable to anoil- or synthetic-based mud.

[0005] To this end the drilling mud with a lowered coefficient offriction according to the present invention comprises a silicate-basedmud and a lubricant selected from the group comprising glycosides,alkylpoly-alkoxyalcohols, alcohol ester polymers, amine phosphates,starch and combinations thereof.

[0006] The amount of lubricant is in the range of from 1 to 15% by mass(kg lubricant per kg of the total mud).

[0007] The preferred additive is a glycoside, and more suitably aglucoside. Glucosides with any carbon number range may be used. By thisis meant mono- or poly-saccharides with carbon number chains of anylength, branched or unbranched. The chains may be attached to anyposition of any ring via oxygen, carboxyl or amino linkages. Theglucoside may also have amino substituted, ester substituted or hydroxylsubstituted alkyl chains. Examples are 4-hydroxybutyl-D-glucopyranoside,4-aminobutyl-D-glucopyranoside, hexadecylphosphato-D-glucopyranoside,hexadecylphosphato-D-glucopyranoside andtrimethylammoniumcarboxymethyl-D-glucopyranoside. An example of analkylpolyalkoxyalcohol is triethylene-oxynonyl-D-glucopyranosideExamples of an alcohol ester polymer are 4-hydroxypropylcarboxy-D-glucopyranoside and stearyl-D-glucopyranoside. Anexamples of an amine phosphate is a lecithin structure with one carboxylgroup replaced by D-glucopyranoside.

[0008] When a silicate mud is used, one preferred additive is apolysaccharide having 16 to 18 carbon chains. The amount of lubricantadded is about 1 to 5% by mass, based upon the total of the mud. Thismakes for a mud to lubricant mass ratio of about 1:0.01 to 1:0.05.

[0009] A second preferred additive for a silicate mud is apolysaccharide having 1 to 7 carbon chains. About 3% to 15% by mass oflubricant is added, for a mud to lubricant mass ratio of between 1:0.03to 1:0.15.

[0010] Another suitable lubricant is starch, and in particular cornsyrup.

[0011] The silicate-base mud according to the invention may furtherinclude an anti-foaming agent and other components such as weightingmaterial.

[0012] The invention is now described in more detail by way of the belowexamples, wherein the lubricity of a silicate mud of compositionaccording to Table 1 has been determined for various lubricants. TABLE 1Composition of the silicate mud used in the examples (excluding thelubricants). Ingredient Amount Water 0.72 barrel Silicate D 0.085 barrelNaOH 0.5 pounds per barrel KCl 12.6 pounds per barrel NaCl 63 pounds perbarrel Barazan D Plus 1 pound per barrel Pac-L 0.5 pounds per barrelN-Drill HT Plus 4 pounds per barrel Barite 138 pounds per barrel

[0013] Wherein Silicate D is a sodium silicate; Barazan D Plus is asynthetic biopolymer, used to control the viscosity and as a suspensionagent; Pac-L is a filtration control agent; N-Drill HT Plus is afiltration control agent; and Barite is a weighting material. The amountof 0.085 barrel of Silicate D gives an equivalent of 12 pounds silicateper barrel water.

[0014] The coefficient of friction (the force parallel to the surfacedivided by the force normal to the surface, which forces act on a bodymoved by the force parallel to the surface) was determined using alubricity tester manufactured by Alkco Services. The conditions were:normal force of 550 Newtons and force parallel to the surface of 2700Newtons.

[0015] Hot rolling (HR) involved rolling the silicate mud for 16 hoursat 150° F.

[0016] The results will be shown below. Table 2 shows the results withlubricants not according to the invention and Table 3 shows the resultswith lubricants according to the invention. TABLE 2 Coefficients offriction with lubricants not according to the invention. Control, withno on after 20 Lubricant lubricant injection minutes HR 3% w Petromaxx0.332 0.307 0.304 ND 3% w Deripohat 0.282 0.264 0.262 ND 154-L 3% wDaxad 31 0.324 0.321 0.325 0.312 3% w Gem CP 0.287 0.263 0.262 ND 5% wGem CP 0.287 0.272 0.281 0.295 3% w Jeffamine 0.311 0.256 0.262 0.273ED-600 3% w Ketjenlube 0.301 ND 0.283 0.279 1300 3% w Ketjenlube 0.3330.207 0.201 0.233 135 3% w EMI-544 0.294 0.279 0.266 0.251 3% wFinagreen 0.388 0.315 0.312 ND

[0017] Wherein Petromaxx is a polymerized poly butene oil family;Deripohat 154-L is a disodium N-tallow-beta-iminodipropionate; Daxad 31is a sodium salt of maleic acid diisobutylene copolymer solution inwater; Gem CP is a polayalkyleneglycol; Jeffamine ED-600 is and oxirane,methyl-, polymer with oxirane, bis(2-amino-propyl)ether; Ketjenlube 1300is a butanol ester polymer; Ketjenlube 135 is a butanol ester polymer;EMI-544 is a commercial lubricant from MI; and Finagreen is an ester ofnatural fatty acids. The abbreviation ND is used to refer to notdetermined. TABLE 3 Coefficients of friction with lubricants notaccording to the invention. Control, after with no on 20 Lubricantlubricant injection minutes HR 3% w methyl 0.336 0.273 0.282 NDglucoside 3% w methyl 0.329 0.261 ND ND glucoside 5% w methyl 0.3290.235 ND ND glucoside 10% w methyl 0.329 0.270 0.223 0.223 glucoside 3%w Glucopon 625 0.308 0.226 0.214 0.205 1.5% w Glucopon 0.326 0.240 0.1940.205 625 and 1.5% w Dehypon LS 36 1% w Daxad 31, 0.295 0.295 0.297 ND1% w Glucopon 625 and 1% w Dehypon LS-36 10 ppb Emulgade 0.285 0.2910.302 0.314 68/50 3% w Glucopon LF-1 0.359 0.207 0.215 0.195 10% w of astarch 0.293 0.222 0.217 0.216 slurry

[0018] Wherein Glucopon 625 is D-glucopyranoside, C₁₀₋₁₆-alkyl; DehyponLS 36 is an ethoxylated, propoxylated lauryl alcohol; Emulgade 68/50 isa mixture of C₁₆₋₁₈-alkyl glucosides and fatty alcohol; Glucopon LF-1 isa mixture of alkyl polyglycosides and ethoxylated propoxylated aliphaticalcohol; and the starch is corn syrup.

[0019] A comparison between the results in the Tables shows theadvantage obtained when using the lubricant according to the presentinvention.

1. A drilling mud with a lowered coefficient of friction comprising asilicate-based mud and a lubricant selected from the group comprisingglycosides, alkylpolyalkoxy-alcohols, alcohol ester polymers, aminephosphates, starch and combinations thereof.
 2. The drilling mudaccording to claim 1, wherein the lubricant is a glucoside selected frommonosaccharides and olisaccharides having 2 to 4 saccharide groups. 3.The drilling mud according to claim 2, wherein the glucoside comprisesbranched or unbranched carbon chains of any length linked by oxygenlinkages to any position of any ring.
 4. The drilling mud according toclaim 2, wherein the glucoside comprises branched or unbranched alkylchains of any length linked by carboxyl linkages to any position of anyring.
 5. The drilling mud according to claim 2, wherein the glucosidecomprises branched or unbranched alkyl chains of any length linked byamino linkages to any position of any ring.
 6. The drilling mudaccording to claim 3, wherein the glucoside has amino substituted alkylchains.
 7. The drilling mud according to claim 3, wherein the glucosidehas ester substituted alkyl chains.
 8. The drilling mud according toclaim 3, wherein the glucoside has hydroxyl substituted alkyl chains. 9.The drilling mud according to claim 1, wherein the mud is asilicate-based mud and the lubricant is a polysaccharide having alkylchains having between 16 and 18 carbon atoms.
 10. The drilling mudaccording to claim 1-9, wherein the concentration of the lubricant isbetween 1 and 5% by mass.
 11. The drilling mud according to claim 1,wherein the mud is a silicate-based mud and the lubricant is apolysaccharide having alkyl chains having between 1 and 7 carbon atoms.12. The drilling mud according to claim 11, wherein the concentration ofthe lubricant is between 3 and 15% by mass.